Ultra short wave signaling



Oct. 20, 1942. K, FRITZ ULTRA-SHORT WAVE SIGNALING Filed May 2', 1940WAVE LEA/G77! MUDULA-TED WAVE lA/PUT CON VERT ED WA VE OUTPUT CONVERTEDWA VE OUTPUT WAVZ" LENGTH MODULATFD WAVE INPUT INVENTOR K F 72 A TORNEYPatented Oct. 20, 1942 ULTRA SHORT WAVE SIGNALING Karl Fritz, Berlin,Germany;

Propel-tr Application May 2, 1940, Serial No.

vested in the Alien Custodian In Germany January 13, 1939 4 Claims. (01.178-44) The present invention relates to amethod of converting phasemodulation, or frequency modulation into amplitude modulation, or viceversa, in the case of ultra-short waves, which method is to be employedmore especially for the demodulation.

In the case of ultra-short waves it is extremely diflicult, as is known,to carry out a uniform modulation with a higher degree of modulation,since the oscillation lines of the generators reveal rupture regions andbecause, furthermore, amplitude variations always entail variations inthe phase and in the frequency and vice versa. If the modulation degreeis very small, the demodulation is obviously very difllcult and freedomfrom distortion can hardly be attained. These difficulties areeliminated in accordance with the present invention in that themodulation degree can be increased to any desired extent in the courseof the conversion process of the one modulation type into the othermodulation type, wherefore the actual demodulator need have but a lowsensitivity.

In accordance with the present invention the modulated wave is appliedto the working circuit across two paths having different travel timesuch that the phase variations of the wave are converted into amplitudevariations and vice versa while increasing at the same time the degreeof modulation.

The present invention can be employed to particular advantage intransmission system which operate with travel time generators forinstance with magnetron tubes, or retarding fleld tubes. In thesegenerators a frequency modulation having a small frequency variation canb conveniently and safely carried out.

In practicing the invention use may be made of a great many diflerentmeasures. ble wire lines, or coaxial lines may be'used, or the hollowtube lines which have come into use recently. It is obvious that anentirely wireless operation with the use of concentrated ultrashort wavelikewise is within the scope of the present invention.

A simple example of execution of the invention is shown in Fig. l inwhich a line L branches into two lines LI and L2 having differentelectric lengths and which then form again a common line. If ahigh-frequency wave arrives from one side of the line whereby thefrequency of said wave is modulated with small variation, this wave willbe split up into two components which after passing through the paths LIand L2 meet again Thus, douindividual waves can constant, thickness ofamplitude modulation it can be easily seen that already the slightestfrequency variations of the original wave result in a high amplitudevariation of the wave resulting from the interference of the two partwaves, if the travel difference is suitable, i. e., if it is chosen insuch manner whereby at the upper limit of the frequency an addition ofthe amplitudes of the two part waves occurs, while at the lower limit asubtraction occurs. The degree of modulation of the resultant wave canbe increased up to 100%. In order to set the resultant degree ofmodulation, it is of advantage to render the electrical length of one ofthe two paths variable.

If the very shortest waves are an arrangement according to Fig. 2 moreespecially is of advantage in which a so-called hollow tube line isconsidered. In'such a line L the wave All shown in broken linespropagates. the end of the line a mirror R of dielectric material isarranged which reflects a part of the wave All into the extension of theline L, namely into the line L! but admits another part. The latter partwhich is designated by A3 passes through a detour loop LI and meetsagain the mirror from the rear thus entering the line L2 in part as waveA4. reflected at the rear to be employed,

part the line L2, etc. ,The directly reflected part of the wave A0 isformed by the two components Al and A2 which derive from the reflectionof the original ray at the front side and rear side of the mirrorsurface. The amplitudes of the waves AI and A2 must have the same phasewhich condition can be easily realized through suitable choice of thethickness, the dielectric added to these waves a second wave which haspassed once, or several times the detour line Ll. Now, if the length ofthe detour loop is suitably dimensioned such as was explained already onhand of Fig. 1, a weak frequency modulation of the wave A0 can beconverted into a 100% amplitude modulation, if the interfering waveshave the same amplitude. The amplitude ratio of the be easily setthrough suitable choice of the various constants (dielectric thereflection plate, etc.) Aside from the conversion of the frequencymodulation into an amplitude modulation also the production of a phasemodulation through is possible. However, it

where they are brought into interference. Now. 55 is to be presupposedhereby that'the travel time The part of Al which is difference of thetwo part waves assumes the order of a modulation period such as can berealized only in case of very high modulation frequencies. Then twowaves having an amplitude-modulated constant phase difierence formtogether a resultant oscillation whose phase depends on the amplitudediflerence of the quantities of the sum, 1. e., the amplitude modulationhas changed into a phase modulation.

In all cases care is to be taken that as much as possible onlyprogressing waves'appear, i. e., thatthe lines are well matched to whichend suitable means are known as such.

' What is claimed is:

1. In means for converting wave length modulations on ultra-highfrequency wave energy into corresponding amplitude modulations onultra-high frequency wave energy, a hollow tube line having an intakeand an output, means for supplying wave length modulated ultra-highfrequency wave energy to said intake, and means within said hollow tub'eline for increasing the length of the path over which some of said waveenergy flows between said intake and said output, whereby the waves infollowing said two paths are relatively displaced in phase and the wavelength modulations thereon are converted to corresponding amplitudemodulations in the wave energy at said output.

2. In a device for converting modulations of one type on ultra-highfrequency wave energy into corresponding modulations of another type onsaid ultra-high frequency wave energy, a hollow conductor having anintake opening and an output opening, means for supplying modulatedultra-high-frequency wave energy to said intake, means for derivingmodulated ultra-high frequency wave energy from said output opening, andwave phase displacing means in said conductor between said openings,said phase displacing means including a wave reflector which providespath of different length, for said wave energy, between said openings toproduce conversion of the modulation type.

3. In apparatus for converting modulations of a given character on waveenergy into corresponding modulations of a different character on waveenergy, a wave guide having an opening through which said firstmentioned wave energy, a given characteristic of which is modulated, isfed to said guide and having an opening from which said second mentionedwave energy, a different characteristic of which is modulated, isderived, and wave phase displacing means within said guide soconstructed and arranged as to cause portions of the wave energy tofollow paths 1 of different length as they pass from said firstmentioned opening to said second mentioned opening, and to convert themodulations of one character to modulations of a different character.

, 4, In a device for converting wave length modulations on ultra-highfrequency wave energy into corresponding amplitude modulations on saidultra-high frequency wave energy, a branched wave path, having an inputand an output, th branches of said wave path comprising tubularwaveguides of different lengths, means for supplying wave length modulatedultra-high frequency wave energy to the input of said branched pathandfor deriving correspondingly amplitud modulated ultra-high frequencywave energy from the output of said branched paths, said branched pathsof difierent'lengths being so constructed and arranged as to producerelative phase displacement in the wave energy portions flowingthereover from said input to said output to convert the wave lengthmodulations thereon to corresponding amplitude modulations.

KARL FRITZ.

